The present invention relates to a new and novel microencapsulation of solid phase scintillators in gels that are permeable to selected diffusible labels carrying radioactive sources capable of activating the encapsulated scintillator. These microencapsulated scintillators have been used to develop a method for dynamically monitoring the free concentration of diffusible, radioactive-tagged substances in fluid systems.
In biological systems, it is frequently important to quantify uptake, binding, or release of soluble substances by colloidal or macroscopic phases such as cells, sub-cellular particles, or macromolecules. Examples include cellular uptakes of various drugs, the release of cellular catabolites into the blood stream, blood serum levels of various drugs, enzymes, and hormones, and the presence or absence of specific immunoglobulins in the serum of a patient.
Generally, uptake or release is measured either directly by assaying the macroscopic phase after separation from its normal bathing medium, or indirectly by determining the free concentration of the solute. Although a wide variety of analytical techniques (see, for example, S. Ramos, S. Schuldiner, and H. R. Kaback, Methods in Enzymology, Volume IV, part F, pages 680-688; Academic Press, New York 1979) are currently used to obtain these measurements, no single procedure is applicable in every instance. Most procedures are either relatively insensitive, exhibit poort time resolution, or are applicable to a relatively limited group of solutes.